The access points
installed at T3, IGI Airport, New Delhi are of Cisco make, Internal access
points with internal antennas. This is depicted in the below images –
Cisco access points
can be installed in two modes –
i.
Lightweight
installation –
In this mode, access points
make a secure tunnel with the wireless controller and pass all the user traffic
to the controller. Based on configuration, controller take appropriate actions
and process the traffic. Advisable for large/enterprise
setup.
ii.
Autonomous
installation –
In this mode, access points
play the role of controller also and process the traffic as per policy. Ideal
for small setup.
I roam around at various corner of the floor after connecting to
wireless and I didn’t face any connection drop (or re-authentication issues).
This is a roaming functionality which usually possible only in controller based
model. This cause me believe that wireless setup installed at T3, IGI Airport,
New Delhi is controller based setup.
SSID and
other information’s –
SSID announced at T3 was ‘Tata
Docomo Wi-Fi’ and it was an open ssid (service set identifier). So, from
the name itself it was clearly visible that Wi-Fi service is provided by Tata
Docomo (why will anyone else do the advertisement for Tata Docomo J).
After connecting to the SSID, all the user traffic is diverted to the
captive portal which asked for OTP based authentication and only after
successful authentication, user is allowed to access the network (Internet).
From the above screen shots, we are able to find out some useful
information like network segment, signal strength, interference and about
802.11 protocol used.
Network – The IP segment used for
wireless was 100.77.32.0/20 which belongs to 100.64.0.0/10 super net which is
reserved as ‘Shared Address Space’
by IANA and is described in RFC 6598.
802.11 information – I was connected to wireless
network over 802.11n standard in 2.4 GHz band, over channel number 6 and
channel width was 20MHz (.11n standard works on both the band i.e., 2.4GHz and
5GHz). Connection speed was 145Mbps (which is fairly good) and MCS Index was 15.
Signal strength – RSSI value of the connection
was -57dBm, which is fairly good as per standards and noise was -96dBM, which
is negligible. So, we can figure out that interference was very low, or you can
say, it was nearly negligible (and this was expected because wireless network
was confined in the airport, which is under the reach of limited persons only).
Authentication
SSID announced for guest access
was of web-auth type; means it was
open (anyone can come & connect) and all the user traffic was diverted to the
captive portal, which asked for user authentication through OTP before allowing
the user to access the network.
captive portal seeking user information
Website which asked for user
information was https://hs.tatadocomo.com/ttsl/home.do, hosted over
public ip address (i.e., 14.194.199.10) but only accessible when you are
connected through their Wi-Fi. Website was over SSL/TLS which is a best
practice in these cases.
captive portal after success authentication
After successful authentication, user
is allowed to access the Wi-Fi for 45 mins without any charges. Above image depicts
that this (in my case when I took the screen shot, 44 Min 44 Sec are left) and
after that you have to purchase the coupon to access the wireless and same is
available on the captive portal in the denominations of 20, 50 or 100. The
white space visible over voucher images is the space for Ads which was blocked
by Ad Block extension.
Speed Test
and Uplink Information
In 802.11 information part, I
mentioned that I was connected over 145Mbps, which is a theoretical connection
speed based on Tx power, Rx power, RSSI values, Noise, Modulation and certain
other factors. The actual speed which I measured through speed test utility is
shown below –
Speed test results show a download speed of 22 Mbps and upload speed of
32 Mbps which is much better than the average broadband speed in India.
If I talk about the up-link which
is used for upstreaming the Wi-Fi at T3, I was going out through Tata Docomo’s
network and my public IP was 49.248.225.35
This shows that Tata Docomo
provides end-to-end wireless network at T3 which includes wireless access
points, controller and up-link for internet reachability.
